1. Field of the Invention
The present invention relates generally to the field of a universal joint technology, which is used for the purpose of angle adjustment.
2. The Prior Arts
In light of many different situations, it usually needs a universal joint device to solve the problem of dead angles on some actions.
According to FIG. 5, it shows a known universal joint structure, which has a sphere head A located internally in a body, where the sphere head A has a quadrant orifice A1 penetrating through both ends, and the sphere head A is being linked to the body by a spline shaft B which is penetrating through the quadrant orifice A1. In addition, there are bearing plate C and spring D installed for connecting inner area in-between the sphere head A and the body, and hence frictional action force will be generated further in-between bearing plate C and sphere head A by the time the spring D is pushing against bearing plate C. Therefore, when it is combined with adjusting the angle for ferrule A2 of the sphere head, the ferrule A2 will be fixed and locked automatically if the bearing plate C is pushing against the sphere head A. However, there is a limitation on action force generated by the spring. Even though the ferrule has already been locked at a particular angle, its adjusted angle would be very easy to be changed if it is effected by some other external action force, and the turning angle of the sphere is also directly subjected to the taper degree of the quadrant orifice. In other words, the conventional universal joint structure shown in FIG. 5 is suitable only for the micro tool or instrument requiring a minimal action force with a small degree of adjustable range.